Average Recoveries Of Target Compounds Research Articles

Residues and Safety Evaluation of Etoxazole, Bifenazate and Its Metabolite Bifenazate-diazene in Citrus Under Open-Field Conditions.

The residues of bifenazate (sum of bifenazate and bifenazate-diazene) and etoxazole in whole citrus and pulp collected from twelve regions of China were monitored and their chronic dietary risk to consumer were also evaluated. The citrus samples were extracted by a QuEChERS (quick, easy, cheap, effective, rugged, and safe) method, and analyzed by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The average recoveries of target compounds were ranged from 83 to 100% with relative standard deviations (RSDs) of 0.59-11.8%. The limits of quantification (LOQs) for three analytes were 0.01mg/kg. At the interval to harvest of 20 and 30days, the residues of total bifenazate and etoxazole were from below 0.02 to 0.26mg/kg and from below 0.01 to 0.30mg/kg in citrus samples. The chronic risk quotients (RQs) were below 100%, indicating no unacceptable risk to consumers.

Dispersive liquid-liquid microextraction based on solidification of floating organic droplets combined with high performance liquid chromatography-tandem mass spectrometry for determination of benzotriazole ultraviolet stabilizers in seawater

A novel dispersive liquid-liquid microextraction method based on solidification of floating organic droplets (DLLME-SFO) technique was developed for the determination of seven benzotriazole ultraviolet (UV) stabilizers in seawater samples by high performance liquid chromatography with tandem mass spectrometry. The optimal liquid-liquid microextraction experiment conditions were as follows: 20 μL of 1-dodecanol as extraction solvent, 400 μL of methanol as dispersive solvent, 8% (mass percentage) NaCl, pH of the sample below 6, vortex oscillation extraction time in 2 min. The separation of target compounds was achieved by combining a Hypersil GOLD analytical column (150 mm x 2.1 mm, 5 μm) with methanol-water as mobile phase with gradient elution program. Quantitative determination by ESI-MS/MS was achieved using positive ion mode with multiple reaction monitoring mode. The proposed method showed good linearity with the correlation coefficients all above 0. 99. The blank samples were spiked at three levels and the average recoveries of target compounds ranged from 68.3% to 127.5% with the RSDs from 0.9% to 15.2%. The limits of detection (LODs) and limits of quantification (LOQs) of the method for the seven target compounds were in the ranges of 0.001-0.090 μg/L and 0.003-0.300 μg/L, respectively. The developed method was successfully applied for the analysis of the UV stabilizers in seawater at Dalian seashores, and some of the benzotriazoles were detected. The method is simple, rapid, environment friendly, highly sensitive and suitable for rapid analysis of benzotriazole UV stabilizers in seawater.

Development of “one-pot” method for multi-class compounds in porcine formula feed by multi-function impurity adsorption cleaning followed ultra-performance liquid chromatography–tandem mass spectrometry detection

A novel and efficient determination method for multi-class compounds including β-agonists, sedatives, nitro-imidazoles and aflatoxins in porcine formula feed based on a fast "one-pot" extraction/multifunction impurity adsorption (MFIA) clean-up procedure has been developed. 23 target analytes belonging to four different class compounds could be determined simultaneously in a single run. Conditions for "one-pot" extraction were studied in detail. Under the optimized conditions, the multi-class compounds in porcine formula feed samples were extracted and purified with methanol contained ammonia and absorbents by one step. The compounds in extracts were purified by using multi types of absorbent based on MFIA in one pot. The multi-walled carbon nanotubes were employed to improved clean-up efficiency. Shield BEH C18 column was used to separate 23 target analytes, followed by tandem mass spectrometry (MS/MS) detection using an electro-spray ionization source in positive mode. Recovery studies were done at three fortification levels. Overall average recoveries of target compounds in porcine formula feed at each levels were >51.6% based on matrix fortified calibration with coefficients of variation from 2.7% to 13.2% (n=6). The limit of determination (LOD) of these compounds in porcine formula feed sample matrix was <5.0 μg/kg. This method was successfully applied in screening and confirmation of target drugs in >30 porcine formula feed samples. It was demonstrated that the integration of the MFIA protocol with the MS/MS instrument could serve as a valuable strategy for rapid screening and reliable confirmatory analysis of multi-class compounds in real samples.

Determination of 48 fragrance allergens in toys using GC with ion trap MS/MS

This paper presents a method for the simultaneous determination of 48 fragrance allergens in four types of toys (plastic toys, play clays, plush toys, and paper toys) based on GC with ion trap MS/MS. Compared with single-stage MS, MS/MS is superior in terms of the qualification and quantification of a large range of compounds in complicated matrices. Procedures for extraction and purification were optimized for each toy type. The method proved to be linear over a wide range of concentrations for all analytes with correlation coefficients between 0.9768 and 0.9999. Validation parameters, namely, LODs and LOQs, ranged from 0.005-5.0 and from 0.02-20 mg/kg, respectively. Average recoveries of target compounds (spiked at three concentration levels) were in the range of 79.5-109.1%. Intraday and interday repeatabilities of the proposed method varied from 0.7-10.5% and from 3.1-13.4%, respectively. The proposed method was used to monitor fragrance allergens in commercial toy products. Our findings indicate that this method is an accurate and effective technique for analyzing fragrance allergens in materials composed of complex components.